We have searched for exclusive production of exotic charmonia in the reaction μ+N→μ+(J/ψπ+π±N using COMPASS data collected with incoming muons of 160 GeV/c and 200 GeV/c momentum. In the J/ψπ+π mass distribution we observe a signal with a statistical significance of 4.1 σ. Its mass and width are consistent with those of the X(3872). The shape of the π+π mass distribution from the observed decay into J/ψπ+π shows disagreement with previous observations for X(3872). The observed signal may be interpreted as a possible evidence of a new charmonium state. It could be associated with a neutral partner of X(3872) with C=−1 predicted by a tetraquark model. The product of cross section and branching fraction of the decay of the observed state into J/ψπ+π is determined to be 71±28(stat)±39(syst) pb.

Original languageEnglish
Pages (from-to)334-340
Number of pages7
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
StatePublished - 10 Aug 2018


FundersFunder number
National Science Foundation1812377, PHY-1506416
National Science Foundation
Center for Scientific Review
California Department of Fish and Wildlife
Seventh Framework Programme283286
Seventh Framework Programme
Deutsche Forschungsgemeinschaft
Japan Society for the Promotion of Science
Ministry of Education, Culture, Sports, Science and Technology
Ministry of Education, Youth and ScienceLG13031
Ministry of Education, Youth and Science
Israel Academy of Sciences and Humanities
Narodowym Centrum Nauki2017/26/M/ST2/00498
Narodowym Centrum Nauki
Ministry of Science and Technology, Taiwan
Seventh Framework Programme
Bundesministerium für Bildung und Frauen
Fundació Catalana de Trasplantament123600/2011, CERN/FIS-NUC/0017/2015, 116376/2010
Fundació Catalana de Trasplantament


    • Exotic charmonia
    • Photoproduction
    • Tetraquark
    • X(3872)


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